Power Surge Protection

Power surge protection comes in all shapes and sizes. What should you look for?

Volt Clamping

Most devices in stores will not offer specifications better than UL’s 400 volt clamp rating. This means spikes will rise to 400 volt levels before they are contained. If this is from the bottom of the sine wave, the uncontained spike may actually rise to nearly 570 volts! Your equipment will be damaged every time the photocopier fires off a copy; or transients jolt from air conditioners and other motors. Look for surge protection devices rated at 210 – 330 volts clamping – the best!

Sine Wave Tracking

Some devices in stores do not have sine wave tracking. It’s a high-tech capability that clamps spikes tightly against the sine wave. This prevents spikes from rising too high.


Most hardware store devices have no warranty or only a one-year warranty. Look for warranties up to $50,000 in warranty protection.

Let-Through Voltage

This is rarely mentioned in some devices but is very important. For example, a quality protector under conditions of 6,000 volts and 200 amps only allows 10 volts through. Lesser devices have much higher let-through voltage.

Joule Rating

This is a measure of how much damaging energy the suppressors can handle. The higher rating the better. Many don’t mention this, or they range from the 50 to 200 joule level. These low ratings mean that their devices are not made to handle serious power disturbances like lightning. Look for devices to handle up to 1,140 joules.

Peak Amps

A similar energy absorbing rating is called “peak current,” measured in amps (more accurate than joule ratings).

Telephone & Cable Line Protection

If you are attached by a modem to the outside world, on the Internet for example, you need this feature. Telephone lines are antenna systems that direct powerful surges right into the heart of your computer. The same goes for cable/coax lines.

Noise Attenuation

Electro-Magnetic Interference (EMI) and Radio Frequency Interference (RFI) are disruptions on the smooth AC power line sine wave. Lightning, generators, radio transmitters or even household appliances can cause this noise on the power line. This noise shows up as glitches or errors on computer screens, or “snow” on a TV.

Beware of Savings Claims

Power surge protection devices are designed to protect your equipment, but they cannot and will not lower your electric bill. Click here for more information.